A heart attack occurs when the blood supply to part of the heart
muscle itself -- the myocardium (mi"o-KAR'de-um) -- is severely
reduced or stopped. The medical term for heart attack is
myocardial infarction (mi"o-KAR'de-al in-FARK'shun).
The reduction or stoppage happens when one or more of the coronary
arteries supplying blood to the heart muscle is blocked. This
is usually caused by the buildup of plaque (deposits of fat-like
substances) due to atherosclerosis (ath"er-o-skleh-RO'sis).
The plaque can eventually burst, tear or rupture, creating a "snag"
where a blood clot forms and blocks the artery. This leads to
a heart attack. A heart attack is also sometimes called a
coronary thrombosis (throm-BO'sis) or
coronary occlusion (o-KLOO'zhun).

If the blood supply is cut off for more than a few minutes, muscle
cells suffer permanent injury and die. This can kill or disable
someone, depending on how much heart muscle is damaged.

Sometimes a coronary artery temporarily contracts or goes into
spasm. When this happens the artery narrows and blood flow to
part of the heart muscle decreases or stops. We're not sure what
causes a spasm. But a spasm can occur in normal-appearing blood
vessels as well as vessels partly blocked by atherosclerosis.
A severe spasm can cause a heart attack.

How Can I Reduce My Chances of a Heart Attack?

The American Heart Association has identified six key risk factors
people can treat or modify to reduce their risk of a heart attack.
Addressing these risk factors can have immediate benefits to your
overall health and well being.

Extensive clinical and statistical studies have identified several
factors that increase the risk of coronary heart disease and heart
attack. Major risk factors are those that research has shown significantly
increase the risk of heart and blood vessel (cardiovascular) disease.
There are other factors associated with increased risk of cardiovascular
disease, but their significance and prevalence haven't yet been
precisely determined. These are called contributing risk factors.

The American Heart Association has identified several risk factors.
Some of them can be modified, treated or controlled, and some
can't. The more risk factors you have, the greater your chance
of developing coronary heart disease. Also, the greater the level
of each risk factor, the greater the risk. For example, a person
with a total cholesterol of 300 mg/dL has a greater risk than
someone with a total cholesterol of 240 mg/dL, even though everyone
with a total cholesterol greater than 240 is considered high-risk.

What are the major risk factors that can't be
changed?

Increasing age ? About four out of five people who die of coronary
heart disease are 65 or older. At older ages, women who have heart
attacks are more likely than men are to die from them within a
few weeks.

Male sex (gender) ? Men have a greater
risk of heart attack than women do, and they have attacks earlier
in life. Even after menopause, when women's death rate from heart
disease increases, it's not as great as men's.

Heredity (including Race) ? Children
of parents with heart disease are more likely to develop it themselves.
African Americans have more severe high blood pressure than Caucasians
and a higher risk of heart disease. Heart disease risk is also
higher among Mexican Americans, American Indians, native Hawaiians
and some Asian Americans. This is partly due to higher rates of
obesity and diabetes. Most people with a strong family history
of heart disease have one or more other risk factors. Just as
you can't control your age, sex and race, you can't control your
family history. It's even more important to treat and control
any other risk factors you have.

What are the major risk factors you can modify,
treat or control by changing your lifestyle or taking medicine?

Tobacco smoke ? Smokers' risk of heart
attack is more than twice that of nonsmokers. Cigarette smoking
is the biggest risk factor for sudden cardiac death. Smokers have
two to four times the risk of nonsmokers. Smokers who have a heart
attack also are more likely to die and die suddenly (within an
hour). Cigarette smoking also acts with other risk factors to
greatly increase the risk for coronary heart disease. People who
smoke cigars or pipes seem to have a higher risk of death from
coronary heart disease (and possibly stroke) but their risk isn't
as great as cigarette smokers'. Constant exposure to other people's
smoke increases the risk of heart disease even for nonsmokers.

High blood cholesterol ? As blood cholesterol
rises, so does risk of coronary heart disease.. When other risk
factors (such as high blood pressure and tobacco smoke) are present,
this risk increases even more. A person's cholesterol level is
also affected by age, sex, heredity and diet.

High blood pressure ? High blood pressure
increases the heart's workload, causing the heart to enlarge and
weaken. It also increases your risk of stroke, heart attack, kidney
failure and congestive heart failure. When high blood pressure
exists with obesity, smoking, high blood cholesterol levels or
diabetes, the risk of heart attack or stroke increases several
times.

Physical inactivity ? An inactive lifestyle
is a risk factor for coronary heart disease. Regular, moderate-to-vigorous
physical activity helps prevent heart and blood vessel disease.
The more vigorous the activity, the greater your benefits. However,
even moderate-intensity activities help if done regularly and
long term. Exercise can help control blood cholesterol, diabetes
and obesity, as well as help lower blood pressure in some people.

Obesity and overweight ? People who
have excess body fat ? especially if a lot of it's in the waist
? are more likely to develop heart disease and stroke even if
they have no other risk factors. Excess weight increases the strain
on the heart. It also raises blood pressure and blood cholesterol
and triglyceride (tri-GLIS'er-íd) levels, and lowers HDL
("good") cholesterol levels. It can also make diabetes
more likely to develop. Many obese and overweight people may have
difficulty losing weight. But by losing 10 to 20 pounds, you can
help lower your heart disease risk.

Diabetes mellitus (di"ah-BE'teez or di"ah-BE'tis
meh-LI'tis) ? Diabetes seriously increases your risk of
developing cardiovascular disease. Even when glucose levels are
under control, diabetes greatly increases the risk of heart disease
and stroke. About two-thirds of people with diabetes die of some
form of heart or blood vessel disease. If you have diabetes, it's
extremely important to work with your healthcare provider to manage
it and control any other risk factors you can.

What other factors contribute to heart disease
risk?

Individual response to stress may
be a contributing factor. Some scientists have noted a relationship
between coronary heart disease risk and stress in a person's
life, their health behaviors and socioeconomic status. These
factors may affect established risk factors. For example, people
under stress may overeat, start smoking or smoke more than they
otherwise would.

Sex hormones seem to play a role
in heart disease. It's well known that men have more heart attacks
than women do before women reach the age of menopause. Several
population studies show that the loss of natural estrogen as
women age may contribute to a higher risk of heart disease after
menopause. If menopause is caused by surgery to remove the uterus
and ovaries, the risk of heart attack rises sharply. If menopause
occurs naturally, the risk rises more slowly.

If you've had a natural or surgical menopause,
you may be considering estrogen replacement therapy (ERT) or
hormone replacement therapy (HRT). ERT and HRT may increase
your risk of some diseases and health conditions. Your healthcare
provider can give you more information and help you make the
best choice.

The early forms of birth control pills,
with higher doses of estrogen and progestin (pro-JES'tin), increased
a woman's risk of heart disease and stroke. That's especially
true for older women who smoked. Newer, lower-dose oral contraceptives
carry a much lower risk of cardiovascular disease, except for
women who smoke or have high blood pressure.

If a woman taking oral contraceptives has other risk factors
(and especially if she smokes), her risk of developing blood
clots and having a heart attack goes up. It rises even more
after age 35. If you take birth control pills, get your blood
pressure, triglyceride and glucose levels checked yearly.

Drinking too much alcohol can raise blood pressure, cause
heart failure and lead to stroke. It can contribute to high
triglycerides, cancer and other diseases, and produce irregular
heartbeats. It contributes to obesity, alcoholism, suicide and
accidents.

The risk of heart disease in people who drink moderate amounts
of alcohol (an average of one drink for women or two drinks
for men per day) is lower than in nondrinkers. One drink is
defined as 1-1/2 fluid ounces (fl oz) of 80-proof spirits (such
as bourbon, Scotch, vodka, gin, etc.), 1 fl oz of 100-proof
spirits, 4 fl oz of wine, or 12 fl oz of beer. It's not recommended
that nondrinkers start using alcohol or that drinkers increase
the amount they drink.